negative pregnancy tests

My boyfriend and I are sexually active, but we've never had intercourse. We've never been completely naked with eachother, and his genitals have never touched mine bare. But we have done manual sex and oral sex. Now with that being said, a few days after my last period in march we messed around, with him touching me down there first, then I gave him a hand job last and he came all over my hand. Right after he did that I cleaned it up by wiping it off. I wasn't near a sink to wash my hands so I just had a towel to clean up. After about 10 minutes we were laying there and I was in my underwear and I used the same hand which had been wiped off to scratch down there..and I got freaked out that maybe there was some left over sperm on my hand?? I could be just freaking out too much..anyways I thought about the what if's all month and stressed, and lost some weight as well. Got my period for april, but it was a lot lighter than normal,sometimes spotting, sometimes regular bleeding, all on and off for about 5 days. I still felt weird afterwards like started feeling sick to my stomach in the mornings, but maybe its because I was still stressing because I had been reading that you can get a light period and still be pregnant so of course I thought, maybe that could be me!! I went to the store to get pregnancy tests to clear my head because im so sick of thinking this. 2 were negative, of course, but for some reason im still feeling weird? My stomach feels like its swelling, but kinda in my upper abdomen, which is strange. and I've been getting some light cramping and lower back pain, which also could be due to ovulation. But I don't know, I'm just over my head here I think. What does everyone else think? Is this all in my head or is it something I should be concerned with??